Multilumen catheter for minimizing limb ischemia

ABSTRACT

A multilumen catheter that maximizes the blood flow into and out of the patient&#39;s vasculature while also providing for passive and/or active perfusion of tissue downstream of where the catheter resides in the vasculature. The inventive catheter comprises a proximal end, a first distal and a second distal end. Lumens extending from the proximal end to each of these distal ends provide for blood circulation within one or between two blood vessels. At least one aperture in one of the lumens positioned near the proximal end provides for active perfusion of blood to the patient&#39;s vasculature downstream of where the aperture resides in the vasculature when the catheter is inserted into the patient for treatment. The inventive catheter may comprise a third lumen positioned entirely within the patient&#39;s vasculature, providing passive perfusion of blood to the patient&#39;s vasculature downstream of where the third lumen resides in the vasculature when the catheter is inserted into the patient for treatment.

RELATED APPLICATIONS

This application is a division of U.S. application Ser. No. 09/876,281,filed Jun. 6, 2001, which is hereby incorporated by reference herein inits entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a multilumen catheter and, inparticular, to multilumen catheters designed to prevent ischemia inpatients when the catheter is positioned within the body.

2. Description of the Related Art

It is often necessary to divert the flow of blood from a patient's bloodvessel back to the same or a different blood vessel as part of treatinga patient suffering from one or more of numerous health impairments,including cardiovascular disease, such as congestive heart failure.Although surgical cut-down procedures can achieve this, percutaneousinsertion of catheters has made this procedure less invasive andtherefore less traumatic to the patient. Still, insertion of a cannulainto the circulatory system can cause complex, and sometimes adverse,reactions within the body.

Some of the percutaneous procedures involve removing blood from the bodyand subsequently returning it to the body. For example, dialysistreatment involves first removing blood from the patient's circulatorysystem, treating the blood outside of the body, and then returning theblood to the patient's circulatory system to perfuse the various tissuesand organs. Depending on the volume of blood flow, cannulae with largecarrying capacity may be necessary. By maximizing the cross-sectionalarea of the cannula, the volume of blood that may be removed and/orreturned to the patient's vascular system via the cannula is maximized.One approach to maximize the cross-sectional area of the cannulainvolves using either two single lumen catheters or a multi-lumencatheter. In a recirculation application, one lumen would function towithdraw blood and one would function to return blood to the patient.One problem with using two single lumen catheters is that it subjectsthe patient to multiple percutaneous insertion procedures, whichcomplicates the procedure and increases the potential for infection andother complications. Therefore, it would be desirable to have a catheterassembly which could be inserted into the patient through a singleinsertion site.

Multilumen catheters in various forms have been employed for thispurpose. For example, multilumen catheters have been made with two,three or more lumens to serve various aspiration and infusion functions,including extracting and returning blood to vessels, taking bloodsamples for testing and providing medications to the patient's vascularsystem. Simple multilumen catheters have been made by providing tworound catheters of equal or nearly equal length joined by a web, or thinstrip. This approach is described in U.S. Pat. No. 5,776,111 to Tesio.Other multilumen catheter designs have a unitary body with at least oneseptum dividing the lumens which extend from a proximal to a distal end.

While multilumen catheters require only a single puncture of theepidermis, their performance is limited in at least two ways. For one,the outer perimeter of the multilumen catheter cannot exceed the innerdiameter of the vessel into which it is inserted. Furthermore, thealready limited cross-sectional area must be divided into at least twolumens, one for withdrawal and one for return. Thus the carryingcapacity of each lumen is further reduced. To supply the same amount ofblood, the velocity and pressure of the blood in the lumens mustincrease over what it would be in the vessel itself. This has thepotential to cause damage to the vessel as blood comes jetting out ofthe return lumen. Also, it may put further stress upon blood cells, evencausing hemolysis. Thus, multilumen catheters must be made as large aspossible to carry enough blood at satisfactory conditions.

Where the size of a catheter approaches the interior size of a vessel,less and less blood can flow around the catheter. As a result, limitedblood supply reaches tissues and organs located downstream of thecatheter in the vascular system. With insufficient perfusion, thetissues downstream of the lumen insertion site suffer from ischemia andbecome oxygen deprived. Prolonged oxygen deprivation can lead to tissuedamage, as is well known in the art. Therefore, it would be desirable tohave a multilumen catheter that can maximize cross-sectional area ofwithdrawal and return lumens while at the same time providing foracceptable levels of blood perfusion of tissue downstream of thecatheter insertion site in the vascular system. It would also beadvantageous to have a multilumen catheter that can also remove bloodfrom one peripheral vessel and return blood to a second peripheralvessel.

SUMMARY OF THE INVENTION

Overcoming many if not all of the limitations of the prior art, thepresent invention comprises a multilumen catheter for directing the flowof blood to and from a patient through a single cannulation site. Thecatheter comprises a proximal end, a first distal end and a seconddistal end. The first distal end extends further from the proximal endthan the second distal end. A first lumen extends between the firstdistal end and the proximal end and a second lumen extends between thesecond distal end and the proximal end. At least one aperture, butpreferably a plurality of apertures may be formed in one of the first orsecond lumens positioned near the proximal end so that the aperturepermits active maintenance or enhancement of perfusion of blood to thepatient's vasculature downstream of where the aperture resides in thevasculature when the catheter is inserted into the patient fortreatment. In an alternative embodiment, the multilumen catheter furthercomprises a third lumen with distal and proximal ends configured to bepositioned entirely within the patient's vascular system. This thirdlumen is configured to permit the passive flow of blood downstream ofthe catheter site to maintain or enhance perfusion.

In one embodiment, a connector formed in the shape of a Y(“Y-connector”) is positioned at the proximal end of the multilumencatheter. One leg of the Y-connector is in fluid communication with thefirst lumen and the other leg of the Y-connector is in fluidcommunication with the second lumen.

Preferably, in an application of the present invention, an outflowconduit of a pumping system is fluidly engaged to one lumen of themultilumen catheter and an inflow conduit of the same system is fluidlyengaged to the other lumen. The inflow and outflow conduits are fluidlycoupled to a pump so that, when connected to the patient, the pumpcirculates blood from one distal end of the multilumen catheter to theother distal end, and also through at least one aperture in one of thefirst or second lumens positioned near the proximal end. In oneapplication, the multilumen catheter of the present invention isincorporated into an extracardiac pumping system for supplementing bloodcirculation in a patient without any component thereof being connectedto the patient's heart. Such a system is described in U.S. Pat. No.6,200,260, which is incorporated herein by reference. The systemincludes, in addition to the multilumen catheter, a pump configured topump blood through the patient at subcardiac rates, an inflow conduitfluidly coupled to the pump to divert blood to the pump from a firstblood vessel, and an outflow conduit fluidly coupled to the pump todirect blood from the pump to a second blood vessel.

The present invention also provides a method for treating a patientusing the multilumen catheter of the present invention. The methodcomprises the step of inserting the multilumen catheter described aboveinto the patient at a single cannulation site of a first blood vessel,locating the catheter such that a first lumen may be in fluidcommunication with a second blood vessel and a second lumen may be influid communication with the first blood vessel, withdrawing blood fromone of said blood vessels through one of the first or said secondlumens, and delivering blood through the other of said first or secondlumens so that blood is delivered upstream and downstream of thecannulation site.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the invention will now bedescribed with reference to the drawings, which are intended toillustrate and not to limit the invention.

FIG. 1 is a schematic of one embodiment of the present inventionmultilumen catheter.

FIG. 2 is a schematic of an alternative embodiment of the presentinvention multilumen catheter.

FIG. 3 is a schematic of an alternative embodiment of the presentinvention multilumen catheter with a distal end comprising a J-tipconfiguration.

FIG. 4 is a schematic of an alternative embodiment of the presentinvention multilumen catheter comprising a Y-connector.

FIG. 5 is a schematic of one application of one embodiment of themultilumen catheter to a patient.

FIG. 6 is an enlarged view of a portion the proximal end of theembodiment shown in FIG. 1 applied to a patient.

FIG. 7 is an enlarged view of a portion the proximal end of theembodiment shown in FIG. 2 applied to a patient.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Turning now to the drawings provided herein, a more detailed descriptionof the embodiments of the present invention is provided below.

With reference to FIG. 1, one embodiment of the present inventioncomprises a multilumen catheter 10 designed to lessen ischemia that canoccur when a large diameter catheter is inserted into a patient's bloodvessel. The multilumen catheter preferably is of unitary constructionand requires only one entry point into the patient's body. Themultilumen catheter 10 comprises at least two lumens: a first lumen 12and a second lumen 14. The first lumen 12 extends from a proximal end 16of the multilumen catheter 10 to a first distal end 18. The second lumen14 extends from the proximal end 16 of the multilumen catheter 10 to asecond distal end 20. The lumens 12, 14 of the multilumen catheter 10may be arranged one of many different ways. For example, the two lumensmay be joined in a side-by-side manner, forming a “figure-8” when viewedfrom the proximal end 16. Alternately, a single cylindrical catheterhousing may contain within it two or more side-by-side lumens. Acylindrical catheter housing could be formed with a diametral septum,i.e. a wall, extending across the cylinder at a diameter. A cylindricalhousing with concentrically positioned lumens is also contemplated.

The first distal end 18 may be formed with one or more distal apertures22, although such apertures may also be located in the second distal end20. The distal apertures 22 may be positioned close together or spacedcircumferentially around the distal end. The apertures 22 serve todecrease the pressure drop across the cannula tip, thereby minimizingdamage to vessel walls from jetting effects. It may also be appropriateto practice methods for directing blood flow so as to minimize damage tovessel walls from jetting effects and from the recoil effect on thecatheter of blood exiting a catheter. The present invention may furthercomprise a tapered tip 24 at the first distal end 18, which facilitatesinsertion and threading of the catheter into the patient. The presentinvention may also further comprise a tapered tip 26 at the seconddistal end 20.

One preferred embodiment of the multilumen catheter further comprises aset of apertures 28 positioned on the catheter 10 near the proximal end16. The apertures 28 are formed on at least one lumen of the catheter toprovide for fluid communication between one of the lumens 12, or 14 ofthe multilumen catheter 10 and the blood vessel in which it resides. Aradiopaque marker 30 may be positioned at the distal end 18 of themultilumen catheter 10. The multilumen catheter could further comprisemarkings 32 near the proximal end of the multilumen catheter which are aknown distance from one or more of the distal ends. These markings 32,as well as the marker 30 can be used to accurately position the catheterwhen applied to the patient.

In another embodiment of the present multilumen catheter shown in FIG.2, the multilumen catheter 110 comprises a third lumen 134 extendingbetween a proximal end 136 and a distal end 138. The lumen 134 ispositioned and sized such that when the multilumen catheter 110 isapplied to the patient (described below), the lumen resides entirelywithin the patient's body. As described above, the lumen 134 may beconnected to the catheter 110 in a variety of ways. The purpose of thethird lumen 134 is configured to permit the passive flow of blooddownstream to the catheter to enhance perfusion. The embodiment shown inFIG. 2 also may have apertures 128 disposed near the proximal end 116 ofthe multilumen catheter 110. As described above, this embodiment mayfurther comprise a tapered tip 140 at the distal end of the third lumen134 and a tapered tip 142 at the proximal end of the third lumen 134 tofacilitate application of the catheter to the patient.

In one variation of the three lumen embodiment the third lumen 134 maybe made of collapsible material. In the collapsed state, the third lumen134 would conform to at least a portion of the outside surface of themultilumen catheter 110. Once applied to the patient, as described inmore detail below, the lumen 134 would be expanded to the deployed stateshown in FIG. 2. This collapsible lumen could comprise a stone basket,or a frame similar to a stent. A stone basket is a structure that can bedeployed within a patient's body and is used to capture objects. Here,the basket is used primarily to create a space between the catheter 110and the vessel wall to permit the passive flow of blood downstream ofthe catheter site to enhance perfusion.

In an alternate embodiment of the multilumen catheter 210, shown in FIG.3, the first distal end 218 is formed in the shape of a J-tip. That is,the opening at the distal end 218 may be curved such that blood exitingthe lumen 212 is directed back along the multilumen catheter 210. Distalaperture(s) 222 may be formed at the bend of the J-tip so that bloodalso exits the lumen 212 and flows distal of the catheter 210. The “J”shape of the multi-lumen catheter tip may be formed and/or maintained bypre-loading it with a coil or with wire reinforcement, or by using ashape-memory material to create and maintain this shape. If the catheteris inserted so that the tip is straight and the “J” shape is deployedafter the catheter inserted into the patient, the catheter may comprisea tapered tip at the first distal end 218, as described above.

Referring to FIG. 4, yet another alternative embodiment of the presentinvention multilumen catheter 310 comprises a Y-connector 334 formed atthe proximal end of the multilumen catheter 310. As described above, thelumens are separated in any suitable way such that fluid communicationis provided between the distal end 318 of the lumen 312 of themultilumen catheter 310 and the proximal end 336 of one leg of theY-connector 334, and fluid communication is provided between the distalend 320 of the lumen 314 of the catheter 310 and the proximal end 338 ofone leg of the Y-connector 334.

Any of the multilumen catheters described herein may be made fromvarious materials to improve their viability in long-term treatmentapplications. For example, it is preferred that the biocompatibility ofthe catheter be improved compared to uncoated catheters to preventadverse reactions such as compliment activation and the like. To preventsuch side effects, the interior lumens of the catheters can be coatedwith biocompatible materials. Also known in the art are anti-bacterialcoatings. Such coatings may be very useful on the outer surface of thecatheter. This is especially true at or about where the catheter entersthe patient's skin. At such a location, the patient is vulnerable tointroduction of bacteria into the body cavity. Anti-bacterial coatingscan reduce the likelihood of infection and thus improve the viability oflong-term treatments.

In one application, the multilumen catheter of the present invention maybe integrated into a pumping system, such as the one described in moredetail in U.S. Pat. No. 6,200,260. Referring to FIG. 5, such a systemcomprises the multilumen catheter 10, an inflow conduit 38, an outflowconduit 40 and a pump 42. One end of the outflow conduit 40 may beconnected to the proximal end of the lumen 12, while the other end isconnected to the inlet of the pump 42. One end of the inflow conduit 38may be connected to the proximal end of the lumen 14, while the otherend is connected to the outlet of the pump 42. This results in a flowfrom the first distal end 18 to the second distal end 20. Of course, theflow direction may be reversed using the same multilumen catheter,resulting in a flow from distal end 20 to distal end 18. In that case,the outflow conduit 40 is connected to the proximal end of lumen 14 andthe inflow conduit 38 is connected to the proximal end of lumen 12.Referring to FIG. 5, the present multilumen catheter 10 whenincorporated into a pumping system may be applied to a patient in anarterial-arterial fashion. Where the multilumen catheter 10 is insertedinto the femoral artery 44 of the patient 46. The radiopaque marker 30which may be incorporated into the distal end 18 of the multilumencatheter is used to track the insertion of the catheter so that tocatheter may be positioned at a desired site within the patient'svascular system. As mentioned above, markings 32 on the proximal endcould also be used to locate the distal end or ends.

In one example, the distal end 18 may be located in the aortic arch 48.The pump draws blood from the patient's vascular system in the area nearthe distal end 18 and into the lumen 12. This blood is further drawninto the lumen of the conduit 40 and into the pump 42. The pump 42 thenexpels the blood into the lumen of the outflow conduit 38. This lumencarries the blood into the lumen 14 of the multilumen catheter 10 andback into the patient's vascular system in the area near the distal end20. As described in greater detail below regarding FIGS. 6 and 7, theapertures 28 and/or the third lumen 134 provide blood flow to thepatient's vasculature downstream of where the multilumen catheterresides in the vasculature to maintain or enhance perfusion of blood.The blood flow in the multilumen catheter may be reversed. In that case,blood is drawn from the patient through distal end 20 and returned tothe patient through distal end 18.

Referring to FIG. 6, the multilumen catheter 10 comprises features thatwill maintain or increase the blood flow to downstream tissue when thecatheter is inserted into the patient. The apertures 28 provide forfluid communication between at least one lumen 12 or 14 and thepatient's blood vessel. The apertures 28, thus, provides activeperfusion of the downstream tissues.

Referring to FIG. 7, the lumen 134 of the embodiment shown in FIG. 2 islocated entirely within the vessel when the catheter 110 is insertedinto the patient. The lumen provides a pathway for blood flow to tissuedownstream of the catheter so that the catheter 110 may maintain orincrease the flow of blood to downstream tissue. The lumen 134, thus,provides passive perfusion. If desired, apertures may be included in oneof the other two lumens to supplement passive perfusion with activeperfusion.

The invention may be embodied in other specific forms without departingfrom its spirit or essential characteristics. The described embodimentis to be considered in all respects only as illustrative and notrestrictive and the scope of the invention is, therefore, indicated bythe appended claims rather than by the foregoing description. Allchanges which come within the meaning and range of equivalency of theclaims are to be embraced within their scope.

1. A multilumen catheter for directing the flow of blood through apatient through a single cannulation site, said catheter comprising: acatheter having a proximal end, a first distal end and a second distalend, said first distal end extending distally further from the proximalend than the second distal end; a first lumen extending between saidfirst distal end and said proximal end, wherein in use said first lumenis curved at said first distal end such that blood exiting the lumen isdirected back along the multilumen catheter; and a second lumenextending between said second distal end and said proximal end.
 2. Themultilumen catheter of claim 1 further comprising means for maintainingor enhancing perfusion to the patient's vasculature and to minimizeischemia downstream of a point of entry of said catheter into a bloodvessel when said catheter is inserted into the patient.
 3. Themultilumen catheter of claim 2, wherein the means for maintaining orenhancing perfusion comprises an active perfusion means.
 4. Themultilumen catheter of claim 3, wherein the active perfusion meanscomprises an aperture.
 5. The multilumen catheter of claim 3, whereinthe active perfusion means is at least one aperture in one of saidlumens positioned near the proximal end.
 6. The multilumen catheter ofclaim 2, wherein the means for maintaining or enhancing perfusioncomprises a passive perfusion means.
 7. The multilumen catheter of claim6, wherein the passive perfusion means is a third lumen having a distaland a proximal end configured to be positioned entirely within thepatient's vascular system.
 8. The multilumen catheter of claim 1,further comprising a Y-connector positioned at the proximal end, whereina first leg of the Y-connector is in fluid communication with said firstlumen and a second leg of the Y-connector is in fluid communication withsaid second lumen.
 9. The multilumen catheter of claim 1, furthercomprising an outflow conduit fluidly engaged to one lumen and an inflowconduit fluidly engaged to the other lumen, said inflow and outflowconduits fluidly coupled to a pump so that when connected to a patient,said pump circulates blood from one distal end of said multilumencatheter to the other distal end and also through at least one aperture.10. The multilumen catheter of claim 1, wherein the first distal end istapered.
 11. The multilumen catheter of claim 1, wherein the seconddistal end is tapered.
 12. The multilumen catheter of claim 1, whereinone of said distal ends comprises at least one distal aperture.
 13. Themultilumen catheter of claim 1, wherein said first distal end comprisesa J-tip comprising a bend.
 14. The multilumen catheter of claim 13wherein said J-tip comprises an aperture positioned at the distal-mostportion of the bend.
 15. The multilumen catheter of claim 1, furthercomprising a radiopaque marker, wherein the radiopaque marker can beused to position the catheter when the catheter is applied to a patient.16. The multilumen catheter of claim 1, further comprising an indicatornear the proximal end, wherein the indicator can be used to position thecatheter when the catheter is applied to a patient.
 17. The multilumencatheter of claim 1, wherein the proximal end has two ports.
 18. Themultilumen catheter of claim 1, wherein the catheter is adapted forinsertion in a patient with the catheter having a continuous peripheryat the skin exit site of the patient.
 19. The multilumen catheter ofclaim 1, wherein said first lumen is curved at said first distal endafter the catheter is inserted into the patient.
 20. The multilumencatheter of claim 1 wherein said first lumen is curved at said firstdistal end before the catheter is inserted into the patient.